Hair loss is a prevalent affliction of many humans, the most common being androgenetic alopecia (AGA) where males lose scalp hair as they get older (i.e., male pattern baldness). Other hair loss afflictions include alopecia areata (AA), female pattern baldness and hair loss secondary to chemotherapy and/or radiation treatment (i.e., secondary alopecia).
Hair is normally divided into two types: "terminal" and "vellus". Terminal hair is coarse, pigmented hair which arises from follicles which are developed deep within the dermis. Vellus hairs are typically thin, non-pigmented hairs which grow from hair follicles which are smaller and located superficially in the dermis. As alopecia progresses, there is a change from terminal to vellus type hair. Other changes that contribute to alopecia are alterations in the growth cycle of hair. Hair typically progresses through three cycles, anagen (active hair growth), catagen (transition phase), and telogen (resting phase during which the hair shaft is shed prior to new growth). As baldness progresses, there is a shift in the percentages of hair follicles in each phase with the majority shifting from anagen to telogen. The size of hair follicles is also known to decrease while the total number remains relatively constant.
A variety of procedures and drugs have been utilized in an attempt to treat hair loss. A common technique involves hair transplantation. Briefly, plugs of skin containing hair are transplanted from areas of the scalp where hair was growing to bald or balding areas of the scalp. This procedure, however, is time-consuming and relatively painful. Other approaches include ultra-violet radiation and exercise therapy.
More recently, the stimulating hair growth has been achieved, although with limited success, by drug therapy. One of the most well-recognized hair-growth agents is sold under the tradename "Minoxidil", as disclosed in U.S. Pat. No. 4,596,812 assigned to Upjohn. However, while the results generated through the use of Minoxidil have appeared promising, there is still a need in the art for improved compositions capable of stimulating the growth of hair in warm-blooded animals. To this end, certain peptide-copper complexes have been found to be effective hair-growth agents. For example, U.S. Pat. Nos. 5,177,061, 5,120,831 and 5,214,032 disclose certain peptide-copper complexes which are effective in stimulating the growth of hair in warm-blooded animals.
While significant progress has been made in the simulation of hair-growth by drug treatment, there is still a need in the art for compounds which have greater stimulatory effect on hair growth. The present invention fulfills this need, while further providing other related advantages.